This Fall I will be teaching a graduate course on "Parallel & Vector
Algorithms in Scientific Computing". During the semester the students
will have to complete individual projects on the Alliant FX/8 and the
Encore Multimax machines at the High Speed Computing Facility of the
University of Iowa. I would like to introduce my students to the newest
algorithms which are suitable for these machines. Therefore I would
appreciate very much any recent reprints and/or preprints of papers
related to the subject of the course as well as any computer programmes
in FORTRAN or C. My address is:

In response to the recent request for more contributions to NA Digest I offer
some thoughts on two interactive matrix computation packages for MSDOS
machines (i.e. PCs): GAUSS and PC-MATLAB. This is not a comprehensive review,
but rather brief notes aimed at informing people who work in matrix
computations about some of the relative merits of these two packages.
All opinions are entirely my own.

Both packages require the presence of an 80(2)87 numeric co-processor. The
80(2)87 implements IEEE standard floating point arithmetic. It provides two
precisions: 32 bit single precision (about 7 decimal digits), and 64 bit
double precision (about 16 digits). All its internal computations are carried
out in 80 bit extended precision.

MATLAB should be familiar to readers of NA digest (see, e.g., the first part
of Axel Ruhe's recent note). As regards PCs it exists in a public domain
version, the original MATLAB (written in Fortran), and in a more recent, much
faster and more extensive version, PC-MATLAB (written in C), which is marketed
by The MathWorks. MATLAB is also available on SUNs and VAXes, in a version
called PRO-MATLAB.

GAUSS, from Aptech systems, is broadly similar to PC-MATLAB in its aims and
features, but it is more strongly oriented towards the statistical analysis of
data, and the manipulation of large sets of data stored on disk. Judging from
the brochures it seems to be popular with statisticians, social scientists and
economists. It exists only in a PC version and was first released in 1984/5.

Both packages are advertised in the July 1987 issue of SIAM News and I refer
you there for further information on prices, etc.

Features in common to both packages: Use double precision. Seem to run the PC
& co-processor at near maximum efficiency (both solve a 90x90 system Ax=b in
under 30 seconds on a PC-AT). Interactive, and procedure driven modes.
Include main linear system and eigenvalue routines from LINPACK and EISPACK.
Powerful matrix syntax. Any single matrix is limited to 8192 elements (thus
n<=90 for an nxn matrix) since it must fit into one 64K MSDOS segment. Can
execute DOS commands from within the program.

Full help screens and demo programs. Neither - rather unfriendly to the
new user.

Line editor based, with capability Full screen editor - roam around the
to recall and edit previous line. screen at will. Execute a sequence
of commands contained within any marked
area of the screen. Recall previous
screen. Save screen to disk.

Main program resides in memory. Uses disk overlays.
FOR loops. No FOR loops - must be simulated using
a DO loop.
Vector elements referenced as X[i]. X[i,1] - must use two subscripts.
B

Access to Hessenberg and Schur These absent - could be added by linking
decompositions, matrix exponential in compiled Fortran code, but this not
and square root, and QZ algorithm. for the feint-hearted!

Control System Toolbox adds new Various add-on modules available, written
commands for control applications. in GAUSS programming language. E.g.
for hi-res graphics (since only three
primitive routines are built in),
unconstrained nonlinear optimisation
(quasi-Newton), nonlinear least squares,
further stats and data handling.

Extremely easy to use, comprehensive On my copy hi-res graphics require a
and impressive graphics. The one CGA adaptor, so I haven't tried them.
program supports all the main I believe other graphics cards are
graphics adaptors. supported in the latest version.

Both packages include powerful programming languages (compiling to some forms
of intermediate code) with procedures and functions. Both enable the user to
to extend or customise the language using procedures. PC-MATLAB's syntax is
the more elegant and concise, but GAUSS has more built-in commands, especially
regarding statistical functions and handling "datasets" on disk. I find that
the GAUSS compiler is fussy about syntax and its error messages are often
extremely unhelpful. GAUSS offers great flexibility over configuration (how
memory is partitioned between symbols and variables, which functions are pre-
loaded etc.) but at the price of complexity.

Summary: Both packages are extremely useful aids to research in matrix
computations, for "n <=90". I recommend both: each has some advantages over
the other. PC-MATLAB is the easier to learn and the more user-friendly, and
would probably be the first choice of most numerical analysts; GAUSS can be
quicker and more convenient for the "power user".

We will be spending our sabbatical year at University of California San
Diego (Mathematics Department) starting September 1, 1987 until June 1988.
We will continue to receive our NA e-mail there.
Biswa and Karabi Datta

Domain Decomposition is a class of methods for solving mathematical physics
problems by decomposing the physical domain into smaller subdomains
and obtaining the solution by solving smaller problems on these subdomains.
The motivation may be : the ability to use different mathematical models
and approximation methods in different subdomains, use of fast direct methods
in subdomains, memory limitations of the computer and suitability for
implementation on parallel computers. Applications can be found in many
areas of scientific computing and related industrial applications,
such as computational fluid dynamics and structural mechanics.

This symposium is a sequel to the First International Symposium on
Domain Decomposition Methods held in Paris in January, 1987.
The aim is to bring together the leading researchers in this rapidly expanding
and highly interdisciplinary field to survey and review the progress that
has been made since the last symposium. There will be approximately 25
invited papers and a limited contributed papers/poster session.
In selecting invited and contributed papers, the organizing committee
will try to keep a balance between the mathematical development, associated
algorithms and their implementation on parallel computers, and
industrial applications.

The deadline for submission is November 1, 1987.
Acceptance will be notified before December 1, 1987.
It is expected that selected papers will be published in a proceedings
about June 1988.
Authors should plan to have a full length paper ready by mid-March 1988.

REGISTRATION

Registration forms, travel and hotel information can be obtained by writing to:

Registration fee is US$100, which includes refreshment, abstracts and one
banquet ticket. Student registration fee is US$50. Extra banquet ticket
is US$25.

RELATED CONFERENCES

The annual AIAA meeting will be held in Reno, Nevada from January 11-14, 1988.
The Third conference on Hypercube Concurrent Computers and Applications
will be held the following week (January 19-20, 1988) in nearby Pasadena.

SPONSOR

Office of Naval Research under an University Research Initiative Grant.

The SCHEDULE package for writing explicitly parallel programs in Fortran
is now available on NETLIB. The purpose of this package is to provide
a tool for constructing portable software for parallel computers. It allows
one to express algorithms with synchronization requirements that are beyond
the capabilities of loop based parallelism normally supported by vendors.
It also provides the capability of dynamic spawning of processes at
run time and interfaces well with existing Fortran libraries. The users
code will port between the parallel computers that SCHEDULE is running on
without change. In addition there is a graphics post processing capability
that is useful for performance analysis and debugging. This trace facility
runs on SUN workstations.